The present invention relates to the interface between a gimbal spring pivot and a load arm in a magnetic disk drive. More specifically, this invention relates to a modification of a bearing surface between the load arm and the gimbal pivot.
Within a disk drive, a load arm supports a head relative to a rotating magnetic disk. The head includes a slider carrying at least one magnetic transducer. The magnetic transducer communicates with individual bit positions on a specified data track within the disk.
A gimbal spring is positioned between the load arm and the slider. The gimbal spring resiliently supports the slider and allows it to move vertically and to pitch and roll about a pivot while the slider follows the topography of the rotating disk.
Magnetic disk drives have traditionally suffered from radial off track errors. These errors occur when the magnetic transducer is not aligned with the correct data track on the magnetic disk. If the transducer is off track, extraneous magnetic fields can be read from adjacent data tracks causing read errors. Analogous radial off track errors, in the form of incorrectly written data, can occur during a write cycle.
A source of radial off track errors is a phenomena referred to in the art as "stick/slip." During read and write cycles, the load arm pivots to position the magnetic transducer over a desired track. The slider laterally accelerates and decelerates during each cycle. The gimbal pivot and the load arm change relative positions due to the dynamic forces on the slider during the cycle. This is known as "slip". On a random basis, the gimbal pivot sticks in the shifted ("slipped") position relative to the load arm and does not return to its original position. This "stick" is caused by the friction between the load arm and the gimbal pivot. A measure of this friction is the frictional coefficient. Since the position of the magnetic transducer is so important, any lateral shift in the slider-gimbal assembly with respect to the load arm may result in radial off track errors.
Suzuki et al U.S. Pat. No. 4,197,566 discloses one attempt at reducing off track errors caused by shifting contact positions between a pivot and a supporting lever for a slider body. Suzuki et al provides first and second gimbal springs disposed about a pivot. Adverse forces near the contact point are reduced to inhibit shifting of contact positions. The configuration shown in Suzuki reduces the "slip" at the expense of added gimbal spring complexity and manufacturing costs.
The prior art lacks a simple method of eliminating radial off track errors caused by the "stick/slip" phenomena.